1. DATA COMMUNICATION & INTERNET
FEBRUARY 2013
By Eng. Anuradha Udunuwara,
BSc.Eng(Hons), CEng, MIE(SL), MEF-CECP, MBCS, ITILv3 Foundation, MIEEE, MIEEE-CS, MIEE, MIET, MCS(SL), MSLAAS
2. Agenda
2
Introduction Access Technologies
OSI Model and Protocols a. Analog Dial Access
b. ISDN Access
a. Data Link Protocols – FR, ATM, PPP
c. Broadband Access
b. Network Protocols - IP
d. ADSL Technology
c. Transport Protocols – TCP
e. Data circuits
d. Application Protocols - SMTP, FTP
f. VPN
LAN WAN Technologies Internet Applications
a. LAN Networking a. Electronic mailing
b. WAN IP Routing b. Web on Internet
c. WAN Switching c. Intranets
d. LAN Bridging d. Extranets
f. VPN Technology e. E-commerce
g. MPLS
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7. King of England King of France
Scriber Scriber
Translator Translator
Negotiator Negotiator
Manager Manager
Mail room Mail room
Envelop Envelop
Delivery Delivery
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8. Please Do Not Throw Sausage Pizza Away
User A
8
User B
Layer 7 Application Application
Presentation Presentation
Session Session
Transport Transport
Network Network
Data Link Data Link
Layer 1 Physical Physical
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9. OSI model
9
prescription of characterizing and standardizing the
functions of a communications system in terms of
abstraction layers (a way of hiding the implementation
details of a particular set of functionality)
Similar communication functions are grouped into logical
layers
A layer serves the layer above it and is served by the
layer below it
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10. TCP/IP vs. OSI
10
Source: http://webpage.pace.edu/ms16182p/networking/protocols.html
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16. Data Link Layer
16
protocol layer that transfers data between adjacent
network nodes in a WAN or between nodes on the
same LAN segment
provides the functional and procedural means to
transfer data between network entities and might
provide the means to detect and possibly correct errors
that may occur in the physical layer
Ex: - ATM, L2TP, IEEE 802.3, Frame Relay, PPP, X.25
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17. ATM
17
a telecommunications concept defined by ANSI and ITU (formerly CCITT) standards for carriage of a
complete range of user traffic, including voice, data, and video signals, and is designed to unify
telecommunication and computer networks
uses asynchronous time-division multiplexing, and it encodes data into small, fixed-sized cells
differs from approaches such as the IP or Ethernet that use variable sized packets or frames
provides data link layer services that run over a wide range of OSI physical Layer links
has functional similarity with both circuit switched networking and small packet switched networking
designed for a network that must handle both traditional high-throughput data traffic (e.g., file transfers),
and real-time, low-latency content such as voice and video
uses a connection-oriented model in which a virtual circuit must be established between two endpoints
before the actual data exchange begins
is a core protocol used over the SONET/SDH backbone of the PSTN and ISDN, but its use is declining in
favor of all IP
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20. FR
20
standardized WAN technology that specifies the physical and logical link layers of digital telecommunications channels using a
packet switching methodology
Originally designed for transport across ISDN infrastructure, it may be used today in the context of many other network
interfaces
Network providers commonly implement Frame Relay for voice (VoFR) and data as an encapsulation technique, used between
LANs over a WAN
Each end-user gets a private line (or leased line) to a FR node
FR network handles the transmission over a frequently-changing path transparent to all end-user extensively-used WAN
protocols
less expensive than leased lines and that is one reason for its popularity
extreme simplicity of configuring user equipment in a FR network offers another reason for FR’s popularity
With the advent of Ethernet over fiber optics, MPLS, VPN and dedicated broadband services such as cable modem and DSL,
the end may loom for the Frame Relay protocol and encapsulation
many rural areas remain lacking DSL and cable modem services. In such cases the least expensive type of non-dial-up
connection remains a 64-kbit/s frame-relay line
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23. PPP
23
a data link protocol commonly used in establishing a direct connection between two
networking nodes
used over many types of physical networks including serial cable, phone line, trunk
line, cellular telephone, specialized radio links, and fiber optic links such as SONET
also used over Internet access connections (now marketed as "broadband")
ISPs have used PPP for customer dial-up access to the Internet, since IP packets
cannot be transmitted over a modem line on their own, without some data link
protocol
Two encapsulated forms of PPP, PPPoE and PPPoA, are used most commonly by
Internet Service Providers (ISPs) to establish a DSL Internet service connection with
customers
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24. Network Layer
24
responsible for packet forwarding including routing through intermediate routers
provides the functional and procedural means of transferring variable length data sequences from a source to a destination
host via one or more networks while maintaining the quality of service functions
Functions of the network layer include:
Connection model: connectionless communication
Example:- IP is connectionless, in that a datagram can travel from a sender to a recipient without the recipient having to send
an acknowledgement
Every host in the network must have a unique address that determines where it is. This address is normally assigned from a
hierarchical system, so you can be "Fred Murphy" to people in your house, "Fred Murphy, 1 Main Street" to Dubliners, or "Fred
Murphy, 1 Main Street, Dublin" to people in Ireland, or "Fred Murphy, 1 Main Street, Dublin, Ireland" to people anywhere in the
world. On the Internet, addresses are known as IP addresses
Since many networks are partitioned into subnetworks and connect to other networks for wide-area communications, networks
use specialized hosts, called gateways or routers to forward packets between networks
Ex: -IPv4, IPv6, ARP, ICMP, IPSec, IGMP, IPX, AppleTalk
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25. IP
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IP is the primary protocol in the Internet Layer of the Internet Protocol Suite
and has the task of delivering packets from the source host to the
destination host solely based on the addresses.
For this purpose, IP defines datagram structures that encapsulate the data
to be delivered
also defines addressing methods that are used to label the datagram
source and destination
connectionless
The first major version of IP, Internet Protocol Version 4 (IPv4), is the
dominant protocol of the internet
successor is Internet Protocol Version 6 (IPv6), which is increasing in use.
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27. X.25
27
an ITU-T standard protocol suite for packet switched
WAN communication
X.25 WAN consists of packet-switching exchange (PSE)
nodes as the networking hardware, and leased lines,
plain old telephone service connections or ISDN
connections as physical links
replaced by less complex protocols, especially the IP
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30. Transport Layer
30
provides end-to-end communication services for
applications within a layered architecture of
network components and protocols
provides convenient services such as connection-
oriented data stream support, reliability, flow
control, and multiplexing
Ex:-TCP UDP
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31. TCP
31
one of the two original components of the suite, complementing the
IP, and therefore the entire suite is commonly referred to as TCP/IP
provides reliable, ordered delivery of a stream of octets from a
program on one computer to another program on another computer
used by major Internet applications such as the WWW, email,
remote administration and file transfer
Other applications, which do not require reliable data stream
service, may use the User Datagram Protocol (UDP), which provides
a datagram service that emphasizes reduced latency over reliability
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32. Application Layer
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an abstraction layer reserved for communications
protocols and methods designed for process-to-process
communications across a IP computer network.
Application layer protocols use the underlying transport
layer protocols to establish host-to-host connections.
DHCP, DHCPv6, DNS, FTP, HTTP, IRC, MGCP, BGP ,NTP
,POP, RTP, RTSP, RIP, SIP, SMTP, SNMP, SSH, Telnet, SSL
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33. FTP
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standard network protocol used to transfer files from one host or to
another host over a TCP-based network, such as the Internet
FTP is built on a client-server architecture and uses separate control
and data connections between the client and the server
FTP users may authenticate themselves using a clear-text sign-in
protocol, normally in the form of a username and password, but can
connect anonymously if the server is configured to allow it.
For secure transmission that hides (encrypts) the username and
password, and encrypts the content, FTP is often secured with
SSL/TLS ("FTPS")
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37. Types of Networks
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1.Local Area Network (LAN)
2.Wide Area Network (WAN)
3.Metropolitan Area Network (MAN)
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38. LAN
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•A group of computers and network communication devices interconnected within
a geographically limited area, such as a building
• Characterized by,
• Transfer data at high speeds
• Exist in a limited geographical area
• Resources are managed by the company running the LAN
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41. WAN
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•Interconnects LANs
• Characterized by,
• Transfer data at low speeds
• Exist in an unlimited geographical area
• Interconnects multiple LANs
• Connectivity and Resources are managed by a Telephone Company
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46. L2 switching vs. L3 Routing
46
Until the destination is Does not flood the
found the network is network
flooded
VLAN reduces
unnecessary flooding
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47. L2 switching
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Media Access Control (MAC) based
VLAN based
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48. L2 switch
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• MAC learning table (forwarding table)
– MAC/VLAN <-> port
• VLAN table – identification/separation (used
for tagging/un tagging)
– VLAN <-> port
A VLAN is assigned to a port by the switch. This is not
dynamic. Need to provision.
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49. Functions of a L2 Switch
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MAC learning (populating the MAC/VLAN table)
Forwarding (uses MAC/VALN table)
If a computer does not send traffic (silent), then all
the traffic coming to that computer come as
flooding (the switch learns the computers MAC by
the source MAC)
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50. Broadcasting
50
Ex:- server advertises its presence to the clients
Single
Client Client
broadcast
domain
L2 Switch
(flood)
Server (broadcast)
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51. VPN
51
L1
L2
L3
Over the Internet
Over SP network
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52. MPLS
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Traffic is switched
Control signal is routed
mechanism in high-performance telecommunications networks that directs data from
one network node to the next based on short path labels rather than long network
addresses, avoiding complex lookups in a routing table
labels identify virtual links (paths) between distant nodes rather than endpoints
can encapsulate packets of various network protocols
supports a range of access technologies, including T1/E1, ATM, Frame Relay & DSL
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54. Ethernet frame: Get me to the other side
54
RSVP-TE signaling
B D
A LDP signaling session (TCP port 646)
E
C
Ethernet Ethernet
MPLS
Outer label 1 Outer label 2 Outer label 3 Outer label 4
Inner label Inner label Inner label Inner label
Ethernet Ethernet Ethernet Ethernet Ethernet Ethernet
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58. Segments of NGN Architecture
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VoIP
IMS Controllers
Control and Signaling Video
CDMA Network Application
Customer FTTx Core Non-IMS Controllers
Equipment Access Network Data
Network Aggregation
xDSL Network IM
Wimax
User Access Aggregation Core Control and Application
Equipments Network Network Network Signaling Network
Network
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59. Access Network
59
Edge of the network
Enable delivery of services for specific markets
Enable the connection of telecommunication
services with subscribers
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61. Data support via voice-grade modems
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• To send data, it is converted into 4 kHz audio (modem)
• Data rate is determined by Shannon's capacity theorem (there is a maximum data rate (bps)
called the "capacity”, that can be reliably sent through the communications channel. The
capacity depends on the BW and SNR) (C) Anuradha Udunuwara
63. Digital Local Loop Technologies
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ISDN
Voice and Data
Longer distance
DSL
Higher speed
Several variants
Different encoding technologies -> different data
transmission rates
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64. ISDN
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a set of communication standards for simultaneous digital
transmission of voice, video, data, and other network services over
the traditional circuits of the PSTN
There are several kinds of access interfaces to ISDN defined as
Basic Rate Interface (BRI), Primary Rate Interface (PRI) and
Broadband ISDN (B-ISDN).
ISDN is a circuit-switched telephone network system, which also
provides access to packet switched networks, designed to allow
digital transmission of voice and data over ordinary telephone
copper wires
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66. DSL technologies
ADSL ANSI T1.413 Issue 2
66 ITU G.992.1 (G.DMT)
ITU G.992.2 (G.Lite)
ADSL2 ITU G.992.3
ITU G.992.4
ITU G.992.3 Annex J
ITU G.992.3 Annex L
ADSL2+ ITU G.992.5
ITU G.992.5 Annex M
HDSL ITU G.991.1
HDSL2
IDSL
MSDSL
PDSL
RADSL
SDSL
SHDSL ITU G.991.2
UDSL
VDSL ITU G.993.1
VDSL2 ITU G.993.2
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67. G.SHDSL
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Single-pair High-speed Digital Subscriber Line
faster data transmission over copper lines
employs
TC-PAM (Trellis Coded Pulse Amplitude Modulation) modulation
frequencies that include those used by POTS
provide equal transmit and receive (i.e. symmetric) data rates
reach varies according to the loop rate and noise conditions
SHDSL payload may be either
T1 or E1 (full rate or fractional),
multiple ISDN Basic Rate Interface (BRI),
ATM cells or
Ethernet frames (C) Anuradha Udunuwara
68. Factors driving the interest in G.SHDSL
68
Standardization
Improved data rate
offers a two-wire standard operating at 2.3M bit/sec and
four-wire standard operating at 4.6M bit/sec
Improved reach
Spectral compatibility
spectrally compatible with ADSL, causing little noise or
crosstalk between cables
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69. G.SHDSL.bis
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G.SHDSL first published in February 2001
Major updates to G.991.2 were released in December 2003.
Equipment conforming to the 2003 version of G.991.2 is often
referred to by the standard's draft name of G.SHDSL.bis or just
SHDSL.bis.
Updated G.991.2 features:
Optional support for up to four copper pair connections
Optional extensions to allow user data rates up to 5696 kbit/s
Optional support for dynamic rate repartitioning, allowing flexible change of the
SHDSL data rate without service interruption
New payload definitions including Ethernet packet transfer mode (PTM)
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71. Next Generation Access Options
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Next
TDM NGN Generation
POTS ADSL
V5.2 ADSL2+ Access
VDSL FTTx, ETH
WiMAX, LTE
VDSL2
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72. Access network Migration (example)
Current Short Term Long Term
AGW, C5 switch AGW (Cu)
FTTx
Data Network AGW (Cu)
Metro Ethernet Metro Ethernet Metro Ethernet
CDMA CDMA
2G/3G/3.5G 2G/3G/3.5G LTE
WiMAX WiMAX
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76. Electronic mailing
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commonly referred to as email or e-mail
a method of exchanging digital messages from an author to one or
more recipients.
Modern email operates across the Internet or other computer
networks
Some early email systems required that the author and the recipient
both be online at the same time, in common with instant messaging
Today's email systems are based on a store-and-forward model.
Email servers accept, forward, deliver and store messages
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80. 80
SMTP
Simple Mail Transport Protocol - These rules handle outgoing email and get your email from your
computer to your friend's service provider.
POP3
Post Office Protocol - These are the rules governing incoming email. It allows you to keep a set of
messages on a server that mail client can access and download to your computer. Once the email
is downloaded to your computer, it is usually deleted from the server.
IMAP
Internet Mail Access Protocol - This is a different set of rules governing incoming email. IMAP is
more sophisticated than POP3. It allows you to keep messages on a server that you can access
from multiple computers. With IMAP, you can use your mail client to access an email account from
home and Outlook to do this from work and still keep all your messages on the server.
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81. Web on Internet
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WWW
DNS
HTTP
HTTPS
HTML
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82. intranets
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a computer network that uses IP technology to share information,
operational systems, or computing services within an organization
Sometimes, refers only to the organization's internal website, but
may be a more extensive part of the organization's information
technology infrastructure
may be composed of multiple LANs
objective is to organize each individual's desktop with minimal cost,
time and effort to be more productive, cost efficient, timely, and
competitive
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83. internet
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a network between organizations
Internet vs. internet
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84. extranet
84
a computer network that allows controlled access from the outside,
for specific business or educational purposes
In a business-to-business context, an extranet can be viewed as an
extension of an organization's intranet that is extended to users
outside the organization, usually partners, vendors, and suppliers, in
isolation from all other Internet users
An extranet is similar to a DMZ in that it provides access to needed
services for channel partners, without granting access to an
organization's entire network
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87. E-commerce
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type of industry where buying and selling of product or service is
conducted over electronic systems such as the Internet and other
computer networks
E-commerce draws on such technologies as mobile commerce,
electronic funds transfer, supply chain management, Internet
marketing, online transaction processing, inventory management
systems & automated data collection systems
Modern e-commerce typically uses the WWW at least at one point
in the transaction's life-cycle, although it may encompass a wider
range of technologies such as e-mail, mobile devices social media,
and telephones as well
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88. About the Author
88
Eng. Anuradha Udunuwara is a Chartered Engineer by profession based in Sri Lanka. He has nearly a decade
industry experience in strategy, architecture, engineering, design, plan, implementation and maintenance of CSP
Networks using both packet-switched (PS) and Circuit-Switched (CS) technologies, along with legacy to NGN
migration. Eng. Anuradha is a well-known in the field of CSP industry, both locally and internationally.
Graduated from University of Peradeniya, Sri Lanka in 2001 with an honors in Electrical & Electronic Engineering,
Eng. Anuradha is a corporate member of the Institution of Engineers Sri Lanka, a professional member of British
Computer Society, a member of Institution of Electrical & Electronic Engineers, a member of Institution of
Engineering & Technology (formerly Institution of Electrical Engineers), a member of the Computer Society of Sri
Lanka, a life member of Sri Lanka Association for the Advancement of Science, senior member of the Carrier
Ethernet Forum, member of the Internet Society, member of the Internet Strategy Forum, member of the Internet
Strategy Forum Network, member of the Ethernet Academy, member of the NGN/IMS forum and member of the
Peradeniya Engineering Faculty Alumni Association. He is also an ITIL foundation certified and the only MEF-CECP in
the country.
In his spare time Anuradha enjoys spending time with his family, playing badminton, photography, reading and
travelling.
He can be reached at udunuwara@ieee.org
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